Mechanical and geometric advantages in compliant mechanism optimization

Abstract

This paper presents a focused examination of the mechanical and geometric advantages in compliant mechanisms and their ramifications in the design formulations of compliant mechanisms posed as a topology optimization problem. With a linear elastic structural analysis, we quantify mechanical (and geometric) advantage in terms of the stiffness elements of the mechanism's structure. We then analyze the common formulations of compliant mechanism optimization and the role of the external springs added in the formulations. It is shown that the common formulations using mechanical (or geometric) advantage would directly emulate at best a rigid-body linkage to the true optimum design. As a result, the topology optimization generates point flexures in the resulting optimal mechanisms. A case study is investigated to demonstrate the resulting trends in the current formulations.

Key words： compliant mechanisms; topology optimization; mechanical advantage; pseudo rigid-body mechanisms

Acknowledgements

This research work was supported in part by the Research Grants Council of Hong Kong SAR (Project Nos. CUHK416507 and CUHK417708). The author would like to thank Dr. Zen Luo for producing the results in Fig. 6.

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